From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCHv7 02/11] clocksource: add generic dummy timer driver Date: Thu, 06 Jun 2013 18:23:33 +0200 Message-ID: <51B0B785.5080707@linaro.org> References: <1370291642-13259-1-git-send-email-sboyd@codeaurora.org> <1370291642-13259-3-git-send-email-sboyd@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-ea0-f177.google.com ([209.85.215.177]:58363 "EHLO mail-ea0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751147Ab3FFQXk (ORCPT ); Thu, 6 Jun 2013 12:23:40 -0400 Received: by mail-ea0-f177.google.com with SMTP id j14so2843987eak.22 for ; Thu, 06 Jun 2013 09:23:39 -0700 (PDT) In-Reply-To: <1370291642-13259-3-git-send-email-sboyd@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Stephen Boyd Cc: linux-arm-kernel@lists.infradead.org, Mark Rutland , linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, John Stultz , Thomas Gleixner On 06/03/2013 10:33 PM, Stephen Boyd wrote: > From: Mark Rutland >=20 > Several architectures have a dummy timer driver tightly coupled with > their broadcast code to support machines without cpu-local timers (or > where there is a lack of driver support). >=20 > Since 12ad100046: "clockevents: Add generic timer broadcast function" > it's been possible to write broadcast-capable timer drivers decoupled > from the broadcast mechanism. We can use this functionality to implem= ent > a generic dummy timer driver that can be shared by all architectures > with generic tick broadcast (ARCH_HAS_TICK_BROADCAST). >=20 > This patch implements a generic dummy timer using this facility. >=20 > Signed-off-by: Mark Rutland > Acked-by: Marc Zyngier , > Cc: John Stultz > Cc: Thomas Gleixner > Cc: Daniel Lezcano > [sboyd: Make percpu data static, use __this_cpu_ptr(), move to > early_initcall to properly register on each CPU, only > register if more than one CPU possible] > Signed-off-by: Stephen Boyd > --- Except the missing first letter capitalization, in the patch descriptio= n 'add' =3D> 'Add'. Acked-by: Daniel Lezcano > drivers/clocksource/Makefile | 1 + > drivers/clocksource/dummy_timer.c | 69 +++++++++++++++++++++++++++++= ++++++++++ > 2 files changed, 70 insertions(+) > create mode 100644 drivers/clocksource/dummy_timer.c >=20 > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makef= ile > index 8d979c7..1a17d76 100644 > --- a/drivers/clocksource/Makefile > +++ b/drivers/clocksource/Makefile > @@ -29,3 +29,4 @@ obj-$(CONFIG_CLKSRC_SAMSUNG_PWM) +=3D samsung_pwm_t= imer.o > =20 > obj-$(CONFIG_ARM_ARCH_TIMER) +=3D arm_arch_timer.o > obj-$(CONFIG_CLKSRC_METAG_GENERIC) +=3D metag_generic.o > +obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) +=3D dummy_timer.o > diff --git a/drivers/clocksource/dummy_timer.c b/drivers/clocksource/= dummy_timer.c > new file mode 100644 > index 0000000..1f55f96 > --- /dev/null > +++ b/drivers/clocksource/dummy_timer.c > @@ -0,0 +1,69 @@ > +/* > + * linux/drivers/clocksource/dummy_timer.c > + * > + * Copyright (C) 2013 ARM Ltd. > + * All Rights Reserved > + * > + * This program is free software; you can redistribute it and/or mod= ify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > +#include > +#include > +#include > +#include > +#include > + > +static DEFINE_PER_CPU(struct clock_event_device, dummy_timer_evt); > + > +static void dummy_timer_set_mode(enum clock_event_mode mode, > + struct clock_event_device *evt) > +{ > + /* > + * Core clockevents code will call this when exchanging timer devic= es. > + * We don't need to do anything here. > + */ > +} > + > +static void __cpuinit dummy_timer_setup(void) > +{ > + int cpu =3D smp_processor_id(); > + struct clock_event_device *evt =3D __this_cpu_ptr(&dummy_timer_evt)= ; > + > + evt->name =3D "dummy_timer"; > + evt->features =3D CLOCK_EVT_FEAT_PERIODIC | > + CLOCK_EVT_FEAT_ONESHOT | > + CLOCK_EVT_FEAT_DUMMY; > + evt->rating =3D 100; > + evt->set_mode =3D dummy_timer_set_mode; > + evt->cpumask =3D cpumask_of(cpu); > + > + clockevents_register_device(evt); > +} > + > +static int __cpuinit dummy_timer_cpu_notify(struct notifier_block *s= elf, > + unsigned long action, void *hcpu) > +{ > + if ((action & ~CPU_TASKS_FROZEN) =3D=3D CPU_STARTING) > + dummy_timer_setup(); > + > + return NOTIFY_OK; > +} > + > +static struct notifier_block dummy_timer_cpu_nb __cpuinitdata =3D { > + .notifier_call =3D dummy_timer_cpu_notify, > +}; > + > +static int __init dummy_timer_register(void) > +{ > + int err =3D register_cpu_notifier(&dummy_timer_cpu_nb); > + if (err) > + return err; > + > + /* We won't get a call on the boot CPU, so register immediately */ > + if (num_possible_cpus() > 1) > + dummy_timer_setup(); > + > + return 0; > +} > +early_initcall(dummy_timer_register); >=20 --=20 Linaro.org =E2=94=82 Open source software for= ARM SoCs =46ollow Linaro: Facebook | Twitter | Blog